Polarity-switching self-calibrated MIP-PEC sensor based on core-shell S-TiO2/CDs/PCN-224 for accurate detection of tetracycline.

Polarity switching photoelectrochemical (PEC) sensing effectively addresses the issue of false positive or negative results that arise from single signal on or off in PEC systems. In this study, a novel core-shell ternary composite material of S-TiO2/CDs/PCN-224 was constructed by growing PCN-224 on the surface of spherical titanium dioxide (S-TiO2) while simultaneously confining carbon quantum dots (CDs). This ternary composite can produce cathodic and anodic PEC signals under visible (420-800 nm) and ultraviolet (UV)-Vis (320-800 nm) excitation, respectively. Leveraging this characteristic, we constructed a polarity switching PEC sensing system by integrating a tetracycline (TC) molecular imprinting polymer (MIP), enabling dual signals for self-calibration of TC detection results. Notably, the suppression of the cathodic signal due to steric hindrance mitigates interference, while the anodic signal resulting from the advanced oxidation of TC facilitates signal amplification and self-cleaning of the electrode interface, enhancing the reusability of the molecularly imprinted polymer photoelectrochemical (MIP-PEC) sensor. Ultimately, the developed MIP-PEC sensor demonstrates a cathodic mode detection range of 5.00 × 10-13-1.00 × 10-8 mol/L with a limit of detection (LOD) of 3.07 × 10-13 mol/L, and an anodic mode detection range of 5.00 × 10-12-5.00 × 10-6 mol/L, with an LOD of 3.14 × 10-12 mol/L under optimal conditions. Furthermore, it exhibits excellent dual-signal stability, reproducibility, and reusability. This study presents a sustainable and efficient PEC sensing platform capable of achieving polarity switching self-calibration, self-cleaning, and high analytical performance for detecting environmental organic pollutants.